One of the characteristics of hydrolysis (acidification) is that it can improve the biodegradability of wastewater. The original design institute of the Ministry of Textile Industry applied this concept to successfully treat textile wastewater with B/C close to 0.2.

1. Containing PVA and surfactant wastewater

   A domestic dyeing and finishing plant produces COD of 761-904mg/L, BOD5 of 100-169mg/L, B/C of only 0.16, poor gram biodegradability, and refractory chemical pulp polyvinyl alcohol (PVA) in wastewater. Surfactant. If the conventional aerobic treatment is used, the foam will overflow due to aeration and aeration in the aerobic tank, which will result in the failure of the whole process. The COD will decrease after anaerobic treatment, while the BOD will increase, making the biodegradability of the wastewater. The improvement can break the macromolecular PVA and the surfactant, thereby reducing the foam generated by the aeration, and the waste water has a higher removal effect in aerobic. Both the anaerobic reactor and the aerobic reactor used in the experiment used a soft fibrous filler. The anaerobic residence time was 10 h, the aerobic residence time was 10 h, the COD removal rate was 75%, the BOD removal rate was 97%, the PVA removal rate was 71%, and no foam was produced in the aerobic reactor. However, PVA can only be removed by 20% after 8 hours of aerobic treatment, and it cannot be operated due to foaming problems. It can be seen that the use of anaerobic acidic fermentation is very effective.

2, polyester spinning oil wastewater

   In the production process of polyester fiber, in order to improve the fiber properties and improve the fiber woven property, it is necessary to treat the fiber with a spinning oil agent. Spinning oil is mainly composed of some antistatic agents, softeners, penetrants, lubricants and some emulsifiers. These emulsifiers are in turn composed of some anionic surfactants or nonionic surfactants. Such as alkyl phosphate potassium salt, fatty acid polyethylene glycol ester, sodium alkyl ether sulfate and the like. In the oil wastewater, the COD is about 2000 mg/L, and the BOD5 is 350 mg/L, and the B/C is 0.18. The use of various physical and chemical treatment costs is high, biochemical aerobic treatment has a large amount of foam generation, so the anaerobic, aerobic series process is used, and the anaerobic reaction utilizes the acidic fermentation stage. The anaerobic reaction residence time was 10 h, and a soft fiber packed reactor was used. The aerobic method was subjected to a contact oxidation method of 7-8 h. In practice, it was found that the anaerobic reaction increased the B/C ratio from 0.18 to 0.20, and the COD and BOD values increased after anaerobic reaction, indicating that some substances that are difficult to degrade (even compounds that cannot be detected by COD) ) It is easily biodegraded after anaerobic reaction. After anaerobic and aerobic treatment, BOD5 removal can reach 89% and COD removal can reach 89%. This makes the wastewater that cannot be biochemically treated with a general oil concentration of more than 1000 mg/L, and can be stably biochemically treated at a concentration of up to 2000 mg/L.